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Spinal vascular supply
Spinal cord supply is derived principally from the anterior and posterior spinal arteries (from vertebral artery) with supporting segmental supply. Anterior spinal artery The artery supplies the anterior portion of the spinal cord and arises from the intradural segment of vertebral artery in the region of the medulla oblongata. Two arteries unite at the level of the foramen magnum. * Lies in midline on ventral cord surface (in anterior median fissure) * Courses inferiorly from foramen magnum and ends at the conus. * Supplies anterior 2/3 of cord ** Anterior horns, spinothalamic/corticospinal tracts ** Penetrating (central) branches have few collaterals * It is reinforced by segmental branches that enter the vertebral canal Posterior spinal arteries Pair of arteries that supply the respective ipsilateral grey and white posterior columns of the spinal cord. * The posterior spinal arteries arise from either the PICA or vertebral arteries (V3 or V4 segments) * Runs on the entire posterolateral aspect of the spinal cord medial to dorsal root. * It anastomoses with its fellow and with the anterior spinal artery. * Supply posterior 1/3 of cord ** Posterior columns, some corticospinal tracts (variable) * Augmented by posterior radicular arteries (segmental supply) Segmental supply: Origin: * Cervical ** Vertebral arteries (dorsal intersegmental anastomoses) ** Thyrocervical trunk (ventral intersegmental anastomoses) * Thoracic ** Paired intercostal arteries from thoracic aorta ** Pre-, postcentral branches to vertebral bodies ** Pre-, postlaminar, spinal branches to canal, neural arch * Lumbar ** Paired lumbar segmental arteries * Pelvis: ** Posterior division of iliac artery gives lateral sacral branches which gives spinal arteries and enter via anterior sacral foramina ** Anterior division iliac artery gives inferior gluteal artery that supplies sciatic nerve ** Posterior division internal iliac artery gives iliolumbar artery supplies femoral nerve at iliac wing level Course: * Segmental arteries enter canal through intervertebral foramen and penetrate dura where it divides into dural and radiculomedullary branches. ** Dural arteries supply dura, nerve root sleeves ** Radiculomedullary branches supply roots and cord * Radiculomedullary arteries ** Penetrate into the subaracnoid space. ** Radicular branches supply anterior/posterior roots and reinforces the posterior spinal arteries ** Medullary branches anastomose with anterior and posterior spinal arteries, and provide variable supply to cord Artery of Adamkiewicz, also known as the great anterior radiculomedullary artery is the dominant thoracolumbar segmental artery that supplies the spinal cord. * Origin: variable but mostly left and T9-12, and sometimes lumbar. It arises from the segmental branch of the posterior intercostal (thoracic aorta) or lumbar artery (abdominal aorta). It has a diameter of ~1 mm. * Course: ascends on the mid-sagittal surface of the spinal cord, usually less than two-and-a-half vertebral body lengths, with an identifying "hairpin turn" at its anastomosis with the anterior spinal artery. * Branches and supply: anastomosis with the anterior spinal artery, supplying arterial blood to the spinal cord from T8 to the conus medullaris Variant anatomy * Left side origin (73%) * T5 to T8 (15%) * T9-12 origin (62%) * Lumbar origin (26%) Cord nutrient vessels * Central and peripheral systems * Central cord supplied by ASA and centrifugal flow of blood * Peripheral cord by PSA, pial plexus and centripetal flow of blood * Dense capillary network in gray matter of cord Anatomical variants: * Artery of Adamkiewicz as above * Anterior spinal artery ** origin: both vertebral, right only, left only, or at angle of VA fusion ** variable level of fusion or non fusion * Posterior spinal artery ** origin: vertebral, instead of PICA